a. Objectives Core B plays the role of the traditional Data Coordinating Center in multi-site clinical trials research. As such, Core B was designed to provide support to Cores A and C and Projects 1-4 in three broadly defined areas - Data Acquisition, Data Management and Communications, and Data Analysis. The specific objectives of Core B are to (a) facilitate acquisition of data and project specific data for Projects 1-4, (b) develop tools and procedures for ensuring and monitoring the accuracy and confidentiality of all collected data, (c) develop tools and procedures to aid the Principal Investigator, the Executive Committee, and the Scientific Advisory Board in providing scientific oversight and administration of the Program Project, (d) facilitate communication and sharing of data among investigators through state of the art computer networking, and (e) provide statistical support to investigators in the evaluation of Project 1-4 hypotheses.